You're never going to be able to get through this fight without someone making a "bone dragon" joke on the vent channel.

Our Karazhan guide has finally seen the last of the true boss battles added, the bone dragon Nightbane! If you're having trouble with him, or want to know about his loot or abilities, now's your chance!

So you've killed Prince Malchezaar and have cleared all normal bosses from Karazhan. If one of your raid members has been following the long questline Karazhan has (which we will cover later), you will be able to summon Nightbane at the Master's Terrace. Many consider Nightbane the true final boss of this dungeon, as his abilities demand more concentration from your group than any other fight in the zone.